Is the ailment mentioned in the Hadith: "Indeed, Allah has sent down a cure for every ailment except old age," referring only to physical diseases, or does it include non-physical ailments such as brain disorders and autism?

The Hadith (definition), "Allah has not sent down any disease except that He has sent down a cure for it," is general and comprehensive for all physical and psychological illnesses, those known and those unknown. The cure may be unknown at one time, then discovered later, and this is what Ibn Hajar pointed out in Ibn Mas'ud's narration: "Some know it, and some are ignorant of it." Sheikh Al-Sa'di explains that this Hadith encourages learning the medicine of bodies just as the medicine of hearts is learned, and that all the principles and details of medicine are an شرح (explanation/elaboration) of this Hadith. Sheikh Hamza Qasim affirms that there are no incurable diseases without a remedy, and that experiences have proven the truth of this, such as the treatment of tuberculosis after the discovery of penicillin. This includes autism; although its complete cure remains unknown, modern research is revealing its causes and treatment methods, to the extent that some cases are treated with stem cells. Furthermore, spiritual remedies such as charity, kindness, and reliance on Allah, may be more beneficial and faster in effect than material remedies.